In an environment where big drug companies are furiously courting biotechnology companies for licensing deals, Ron Cohen is a hot date. The chief executive of Acorda Therapeutics Inc. in Hawthorne, N.Y., is seeking deep-pocket partners to help him develop new treatments for multiple sclerosis and spinal cord injuries. That makes him potentially attractive to a pharmaceutical industry that doesn’t have many new drugs of its own to work on.Novartis AG invited Cohen to the Ritz-Carlton hotel in Boston this month along with 120 other biotech executives from around the Northeast to schmooze over cocktails and hear executives of the Swiss company brag about their development capabilities and marketing prowess.But despite a high-energy presentation featuring the music of U2 and flashing images of big sales numbers, Cohen remained coy.’'I’m looking at a bewildering array of behemoths out there,” he said. ''I don’t know who does it best."Novartis, Merck & Co., Hoffmann-La Roche Ltd., GlaxoSmithKline and other drug makers are engaged in aggressive campaigns to sign licensing deals with smaller biotechnology companies. Big drug companies are facing patent expirations on many blockbuster drugs over the next five to 10 years. Meanwhile, there has been a steady decline in the number of genuinely new drugs approved by the Food and Drug Administration.